Anatomy of the Ear.pdf

he Anatomy T of the Ear The ear is a sensitive organ of the human body. It is mainly concerned with detecting, transmitting, and transducing sound. Maintaining a sense of balance is another important function performed by the human ear. The Ear Structure The human ear consists of three parts:...

he Anatomy T of the Ear The ear is a sensitive organ of the human body. It is mainly concerned with detecting, transmitting, and transducing sound. Maintaining a sense of balance is another important function performed by the human ear. The Ear Structure The human ear consists of three parts: Outer ear Middle ear Inner ear  Outer Ear The outer ear is made up of cartilage and skin. It collects and channels sound. It includes the auricle or pinna, the visible portion of the ear. The pinna acts as a funnel that directs the sound deeper Auricle into the ear. The Outer Ear  Outer Ear Auricle/Pinna The auricle comprises a thin plate of elastic cartilage covered by a layer of skin. It consists of funnel-like curves that collect sound waves and transmit them to the middle ear. The lobule consists of Auricle adipose and fibrous tissues supplied with blood capillaries. The Outer Ear  Outer Ear External Auditory Meatus It is a slightly curved canal supported by bone in its interior part and cartilage in the exterior part. The meatus or the canal is lined External Auditory Meatus with stratified epithelium and wax glands. The Outer Ear  Outer Ear Tympanic Membrane This membrane separates the middle ear and the external ear. This part receives and amplifies the sound waves. Its central part is known as the umbo. Tympanic Membrane The Outer Ear  Tympanic Cavity Middle Ear It is a narrow air-filled cavity separated from the external ear by tympanic membrane and from inner ear by the bony wall. The tympanic cavity has an auditory tube known as the eustachian tube in its anterior wall. The Middle Ear  Tympanic Cavity Middle Ear It is a narrow air-filled cavity separated from the external ear by tympanic membrane and from inner ear by the bony wall. The tympanic cavity has an auditory tube known as the eustachian tube in its anterior wall. The Middle Ear  Eustachian Tube Middle Ear The eustachian tube is a 4cm long tube that equalizes air pressure on either side of the tympanic membrane. It connects the tympanic cavity with the nasopharynx. The Middle Ear  Ear Ossicles Middle Ear Malleus: A hammer-shaped part that is attached to the tympanic membrane through the handle and incus through the head. It is the largest ear ossicle. Incus: An anvil-shaped ear ossicle connected with the stapes. Stapes: It is the smallest ossicle and also the smallest bone in the human body. The Middle Ear  Inner Ear Bony Labyrinth The bony labyrinth comprises a vestibule, three semi- circular canals, and spirally coiled cochlea. It is filled with perilymph. The Inner Ear  Inner Ear Membranous labyrinth It comprises sensory receptors responsible for balance and hearing. The membranous labyrinth is filled with endolymph and comprises three semi-circular ducts, cochlear duct, saccule and utricle. The sensory receptors include cristae, an organ of corti, and ampullaris maculae. The Inner Ear Functions of the Ear Hearing The ear ossicles in the tympanic cavity receive the vibrations and the stapes pushes the oval window in and out. Functions Hearing This action is passed on to the organ of corti, the receptor of hearing, that contains tiny hair cells that translate the vibrations into an electrical impulse that are transmitted to the brain by sensory nerves. Functions Balance The eustachian tube equalizes the air pressure in the middle ear and maintains the balance. The vestibular complex contains receptors that maintain body balance. Functions Balance The eustachian tube equalizes the air pressure in the middle ear and maintains the balance. The vestibular complex contains receptors that maintain body balance. Functions